Meiosis

  • the process of nuclear division where the number of the chromosomes is halved.
  • produces four daughter cells
  • all daughter cells are haploid
  • chromosomes are shuffled in the process, so that each daughter cell has a unique combination
  • used to create gametes (sperm and egg)

Prophase 1

  • homologous chromosomes pair up (tetrad)
  • crossing-over occurs

Metaphase & Anaphase

  • tetrads line up along the equater, homologs separate

 

Crossing Over - chromosomes exchange sections (increases variability)

Independent Assortment

In addition to Crossing-Over, the process of meiosis ensures that chromosomes are randomly assorted. The following images show three separate possibility for a single cell that has undergone meiosis. Look at all the different combinations.

Sexual Reproduction

- Involves the fusion of gametes, creates unique offspring
- Eggs are much larger than sperm

Image of egg and sperm

Asexual Reproduction

--Does not involve the fusion of gametes
--Offspring are identical to parents
--Budding, Fragmentation (Regeneration), Fission